i need help my betta looks really bad and Im out of ideas...any advice will help

[fifi]

my betta (zero) is not doing to well. The left side of his face is swollen and white. He has these gold spots on him.. Right now his in a 10 gallon hospital tank I just bought for him, With lot of meds but nothing seems to be working. Im treating him for red velvet and only that, but it seems to have no effect now he just sits at the bottom of the tank not eating. Only comes up for air. I had zero for about 5 months he house in a 6 gallon fluvial with a small clown touch and horseface louch and 4 tetras... They are doing fine its just the betta. The ph is 7.2 and the ammonia level is 0.50... Euthanizing him is not a option! I must try to save his life and not give up on him. I have a pic if more needed i can try to get more...thank you from me and zero..lol.. for your help and reply!